Comment #1 on issue 202 by [email protected]: TOP_KEYS feature fixes
http://code.google.com/p/memcached/issues/detail?id=202
As an alternative, including sFlow instrumentation has minimal overhead
(approximately the cost of adding one more performance counter), but
provides full details about keys and operations allowing top keys, missed
keys etc. to be monitored.
sFlow reduces the overhead on the Memcached server by exporting a random
sample of memcache operations to a remote collector. The collector receives
samples from every server in the cluster and calculates top keys etc. This
architecture is extremely scalable and flexible. It is only the collector
that needs to be modified in order to calculate additional statistics (like
top keys with a particular prefix and operation etc). Since sFlow is also
used to monitor network traffic and server performance, the sFlow collector
can put the information together to provide a comprehensive view of cluster
performance.
The patch needed to add sFlow to Memcached is in ticket and could easily be
ported to the 1.6 branch:
http://code.google.com/p/memcached/issues/detail?id=157
For more information on how sFlow works, and the type of data you can get,
see:
http://blog.sflow.com/search/label/Memcache
